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</code></pre><p>√</p><pre class="language-js"><code><span class="token keyword">const</span> a <span class="token operator">=</span> <span class="token punctuation">{</span>
    i<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
    <span class="token function">toString</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    	<span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>i<span class="token operator">++</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
a <span class="token operator">==</span> <span class="token number">1</span> <span class="token operator">&amp;&amp;</span> a <span class="token operator">==</span> <span class="token number">2</span> <span class="token operator">&amp;&amp;</span> a <span class="token operator">==</span> <span class="token number">3</span> <span class="token comment">// true</span>
</code></pre><p>参考
<a href="https://juejin.im/post/5bc5c752f265da0a9a399a62" target="_blank" rel="noopener noreferrer">1</a></p><h2 id="多个await-和-promise-all-的区别"><a href="#多个await-和-promise-all-的区别" aria-hidden="true" class="header-anchor">#</a> 多个await 和 Promise.all 的区别</h2><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">sleep</span><span class="token punctuation">(</span>seconds<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span>resolve <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
        <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
            <span class="token function">resolve</span><span class="token punctuation">(</span><span class="token string">'request done!'</span> <span class="token operator">+</span> Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span> seconds<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre><p>多个await</p><pre class="language-js"><code><span class="token comment">//请求时一个结束之后发起另一个，所以执行时间至少3s</span>
<span class="token keyword">async</span> <span class="token keyword">function</span> <span class="token function">bugDemo</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">await</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">await</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">await</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'done'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token function">bugDemo</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><p>Promise.all</p><pre class="language-js"><code><span class="token comment">//请求时并行处理，时间远小于3s</span>
<span class="token keyword">async</span> <span class="token keyword">function</span> <span class="token function">correctDemo</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">let</span> p1 <span class="token operator">=</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> p2 <span class="token operator">=</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> p3 <span class="token operator">=</span> <span class="token function">sleep</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">await</span> Promise<span class="token punctuation">.</span><span class="token function">all</span><span class="token punctuation">(</span><span class="token punctuation">[</span>p1<span class="token punctuation">,</span> p2<span class="token punctuation">,</span> p3<span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'done'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">correctDemo</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><p>参考
<a href="https://juejin.im/post/59e086fc51882578e310f92d" target="_blank" rel="noopener noreferrer">1</a></p><h2 id="promise-all-实现"><a href="#promise-all-实现" aria-hidden="true" class="header-anchor">#</a> Promise.all 实现</h2><pre class="language-js"><code><span class="token comment">// 简单来说就是把所有要执行的函数都放进一个数组里面，然后数组依次以同步的形式一个一个执行，执行结束后能够接着执行then里面的东西。</span>
Promise<span class="token punctuation">.</span><span class="token function-variable function">all</span> <span class="token operator">=</span> arr <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
    <span class="token keyword">let</span> aResult <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>    <span class="token comment">//用于存放每次执行后返回结果</span>
    <span class="token keyword">return</span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span><span class="token keyword">function</span> <span class="token punctuation">(</span>resolve<span class="token punctuation">,</span> reject<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
        <span class="token function">next</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>    <span class="token comment">//开始逐次执行数组中的函数</span>
        
        <span class="token keyword">function</span> <span class="token function">next</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">then</span><span class="token punctuation">(</span><span class="token keyword">function</span> <span class="token punctuation">(</span>res<span class="token punctuation">)</span> <span class="token punctuation">{</span>
                aResult<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span><span class="token punctuation">;</span>    <span class="token comment">//执行后返回的结果放入数组中</span>
                i<span class="token operator">++</span><span class="token punctuation">;</span>
                <span class="token keyword">if</span> <span class="token punctuation">(</span>i <span class="token operator">==</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">)</span> <span class="token punctuation">{</span>  <span class="token comment">//如果函数数组中的函数都执行完，便把结果数组传给then</span>
                    <span class="token function">resolve</span><span class="token punctuation">(</span>aResult<span class="token punctuation">)</span><span class="token punctuation">;</span>
                <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
                    <span class="token function">next</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
                <span class="token punctuation">}</span>
            <span class="token punctuation">}</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre><h2 id="add-1-2-3-add-1-2-3-柯里化实现"><a href="#add-1-2-3-add-1-2-3-柯里化实现" aria-hidden="true" class="header-anchor">#</a> add(1, 2, 3) === add(1,2)(3)() 柯里化实现</h2><pre class="language-js"><code><span class="token comment">// add 函数柯里化</span>
<span class="token keyword">function</span> <span class="token function">add</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token comment">//建立args,利用闭包特性，不断保存arguments</span>
    <span class="token keyword">var</span> args <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">.</span>slice<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>arguments<span class="token punctuation">)</span><span class="token punctuation">;</span>
       <span class="token comment">//方法一，新建_add函数实现柯里化</span>
    <span class="token keyword">var</span> <span class="token function-variable function">_add</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">if</span><span class="token punctuation">(</span>arguments<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token comment">//参数为空，对args执行加法</span>
            <span class="token keyword">return</span> args<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span>b<span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token keyword">return</span> a<span class="token operator">+</span>b<span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
            <span class="token comment">//否则，保存参数到args，返回一个函数</span>
            <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">.</span>push<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span>args<span class="token punctuation">,</span>arguments<span class="token punctuation">)</span><span class="token punctuation">;</span>
            <span class="token keyword">return</span> _add<span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    <span class="token comment">//返回_add函数</span>
    <span class="token keyword">return</span> _add<span class="token punctuation">;</span>
    
    <span class="token comment">//方法二，使用匿名函数</span>
    <span class="token comment">/*
    return function () {
        if (arguments.length === 0) {
            return args.reduce(function(a,b){return a+b});
        }
        Array.prototype.push.apply(args, arguments);
        return arguments.callee;
    }
    */</span>
<span class="token punctuation">}</span>
</code></pre><p>参考
<a href="https://www.jianshu.com/p/f88a5175e7a2" target="_blank" rel="noopener noreferrer">1</a><a href="https://blog.csdn.net/qq_39207948/article/details/80593715" target="_blank" rel="noopener noreferrer">2</a></p></div><div class="wx-wrapper" data-v-0de8a4bf><p class="wx-txt" data-v-0de8a4bf>欢迎关注</p><img src="http://pn4meizzc.bkt.clouddn.com/wxqr.png" class="wx-img" data-v-0de8a4bf></div><div class="beg-wrapper" data-v-1f1af99c><a href="javascript:;" class="btn show" data-v-1f1af99c><img src="http://pn4meizzc.bkt.clouddn.com/blogshang_log.png" data-v-1f1af99c></a><p class="shang-txt" data-v-1f1af99c>赏不赏，看您心情</p><img src="http://pn4meizzc.bkt.clouddn.com/blogWechatIMG35.jpeg" class="shangImg" data-v-1f1af99c></div><!----><div class="content page-nav"><p class="inner"><span class="prev">
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